1. Field of the Invention
The present invention relates to circuit interrupters generally and, more specifically, to those kinds of circuit interrupters to which a walking beam is connected.
2. Description of the Prior Art
Molded case circuit breakers and interrupters are well known in the art as exemplified by U.S. Pat. No. 4,503,408 issued Mar. 5, 1985, to Mrenna et al., and U.S. Pat. No. 5,910,760 issued Jun. 8, 1999 to Malingowski et al., each of which is assigned to the assignee of the present application and incorporated herein by reference.
It is sometimes desirable or necessary to precisely tie the closing of the contacts of one circuit interrupter with the opening of the contacts of another. Mechanisms, such as what is referred to as a walking beam, have been used in order to accomplish this goal.
A walking beam is typically connected between an initially "ON" circuit interrupter and an initially "OFF" circuit interrupter. One end of the walking beam is positioned in proximity to the operating mechanism of the initially "ON" circuit interrupter, and the other end of the walking beam is positioned so as to prevent the operating mechanism of the initially "OFF" circuit interrupter from allowing the contacts of that interrupter to close. A closing operation is then typically performed on the initially "OFF" circuit breaker whereby the operating mechanism is advantageously placed on the brink of closing the contacts (but cannot due to the walking beam). Thereafter, if the contacts of the initially "ON" circuit breaker are opened due to, for example, a tripping operation, then movement of the walking beam resulting therefrom enables the contacts of the initially "OFF" circuit breaker to quickly close.
Prior art circuit interrupters that may be used in connection with such a walking beam application are typically required to be manufactured with an opening or the like in the interrupter's housing in order to provide access for the walking beam for interfacing with the operating mechanism. Because of the possibility of entry of foreign items into such an opening, such interrupters are not suitable in situations where a walking beam application will not be implemented.
In view of the above, it would be advantageous if a circuit interrupter could be easily adapted for use with a walking beam only if desired.